Shivering is an involuntary, oscillatory muscle contraction that can increase baseline metabolic heat output by up to 600%. But the maximum amount of metabolic heat generation that can be maintained for extended periods of time is a doubling. According to a human electromyographic research, the standard tremor frequency is approximately 200 Hz. Additionally, it revealed that the tremor received a waxing and waning pattern with 4-6 cycles per minute ¹.

Shivering is the outcome of efferent signals traveling via the medial forebrain bundle when a cold stimulus reaches the preoptic area. The preoptic anterior hypothalamus inhibits the posterior hypothalamus to prevent shivering. It was previously believed that the posterior hypothalamus is the source of the central descending pathway of shivering. Whether the reticulospinal neurons receive their synaptic inputs from the preoptic-anterior hypothalamus or the posterior hypothalamus is still unknown¹.

The spinal motor neurons and their axons are the last shared conduit for both coordinated movement and shivering. The electromyography, which displayed clustered discharges, indicated a particular rhythm for cold tremors. Motor neuron excitability is inversely correlated with cell size. When a continuous cold stimulus is applied to the skin or spinal cord, the motor neurons are recruited in an increasing order of magnitude.

Complications of hypothermia and shivering include increased blood loss & reversible coagulopathy, increased blood transfusion, impaired wound healing, increased risk of infection, delayed drug metabolism, left shift of haemoglobin – oxygen dissociation curve, altered mental status, cardiac arrhythmias and Ischemia, increased peripheral vascular resistance, increased myocardial oxygen consumption, increased basal metabolic rate and monitoring artifacts showing aberrant values².

This prospective Randomized double blinded study was conducted among all consenting patients scheduled for lower limb surgeries under spinal anaesthesia, in the Department of Anaesthesiology, at Gulbarga Institute of Medical Sciences Hospital, Kalaburagi. Study population was 100. Duration of study was 18 months (August 2022 to January 2024)

SAMPLE SIZE

Based on the study conducted Kundra T S, et al (2017) 3, we considered the mean difference for the time to cessation of shivering between dexmedetomidine (D) and tramadol (T) group as 10 seconds with a standard deviation of 15 and 23. The sample size was calculated with 80% power and alpha of 0.05 (95% confidence interval), Applying the formula for a two-sided study: n (size per group) =2c/δ2 + 1 where, δ = (µ2–µ1)/σ is the standardized effect size μ1 and μ2 are the means of the two treatment groups σ is the common SD c = 7.9 for 80% power Hence, n = 2 × 7.9/ (1/1.69) 2 + 1 = 46.1. Rounding off, we took the sample size as 50 per group. The sample size thus calculated was found to be 100 with 50 cases in each group.

Inclusion criteria:

1. Patients aged between 18 to 60 years both male and female undergoing elective lower limb surgeries under spinal anaesthesia and reported shivering during surgery.
2. Belonging to American Society of Anaesthesiologists (ASA) Physical status I and
3. Patients whose BMI is in the range of 18 - 9.
4. Patients who are willing to give consent to be a part of the

Exclusion criteria:

1. Patients who do not develop shivering during
2. Patients with contraindications to regional
3. Patients with history of hypersensitivity to amide local anaesthetics, dexmedetomidine and tramadol in the past.
4. Patients who have gone for complications during surgery like shock and prolongation of surgery more than 3 hrs.
5. Failure to decrease the shivering after repeated dosage more than 2
6. Pregnant and lactating
7. Patients with hyperthyroidism, moderate to severe cardiopulmonary disease, hepatic failure psychiatric illness, renal failure, uncontrolled diabetes with autonomic neuropathy, severe bradycardia and hypotension.
8. Excessive hemorrhage needing
9. Failure or incomplete spinal
10. Those with a known history of substance

METHODS OF COLLECTION OF DATA

Institutional Ethical committee approval will be obtained prior to the commencement of the study. Informed written consent will be obtained from all the patients and are explained about that she/he is a part of study, following which detailed pre anaesthetic check up will be done according to the standard protocol . All patients will be monitored during surgery and screened for development of shivering intraoperatively till the sample size of 100 patients reached. The patients who develop shivering during surgery will be allocated to either of the groups (A or B) according to the computer generated random number table. As per the allocation, Group A patients will receive intravenous Dexmedetomidine 0.5μg/kg(study drug)in 100 ml normal saline and Group B will receive intravenous Tramadol 0.5mg/kg(control drug)in 100 ml normal saline for 10 minutes after administration of spinal anaesthesia.

Supplemental oxygen will be administered at the rate of 5-6 L/min via a face mask if necessary. The level of sensory block (defined as loss of pin-prick sensation), will be recorded every minute. Once the adequate levels are achieved and confirmed then surgery will be proceeded. The peak sensory block level will be recorded.

The temperature of the operating room and post anaesthesia-care unit will be kept at 22°C–26°C throughout the study. During the operation, the whole body of the patient, except the head, neck, and operation site, will be covered with one layer of surgical drapes.

Systolic, diastolic and mean arterial pressure, heart rate, oxygen saturation, time interval from spinal block to shivering occurrence, shivering score, sedation score, body temperature at the beginning and 0, 5, 10, 15,30 ,45 ,60 minutes and every half an hour thereafter till the end of surgery or till 180 mins will be observed and recorded.

Rescue drugs for hypotension, bradycardia, and nausea/vomiting will be intravenous atropine (0.6mg), vasopressors and then further infusion of crystalloid (300 mL) fluid as required, and ondansetron 4 mg IV, respectively and rescue drug for shivering will be intravenous injection pethidine (0.5mg/kg) and warm fluids when it recures for more than 2 times. The amount of rescue drugs in each group will be recorded and also the time for cessation, and failure of the drug will be recorded.

STATISTICAL ANALYSIS

Data was analyzed by IBM SPSS 25.0 version software. Collected data were entered in excel sheet and prepared master chart. Through the master chart, tables and graphs were constructed. For descriptive statistics were done mean, standard deviation initially; for quantitative data analysis independent samples “t-” test was used to compare the mean values between two variables for statistical significant. For qualitative data analysis chi- square test and Fisher exact probability tests were applied for statistically significant. P ≤0.05 was considered statistically significant for all comparison.

In the study; Out of 100 sample cases were divided in to two groups, Group-A = Dexmedetomidine were randomly divided 50 (50.0%) samples and Group-B = Tramadol were randomly divided 50 (50.0%) samples. there was statistically. There was statistically no significant difference of mean age between the groups Group-A and Group-B (P>0.05).

In the Group-A Male cases were 38 (76.0%) and in Group-B male cases were 36 (72.0%) and Female cases in Group-A were 12 (24.0%) and Group-B were 14 (28.0%). There was statistically no significant difference of distribution of gender between the Groups- D and Group-B (P>0.05).

Table  1: Comparison of mean axillary temperature (ocelcius) between the group

The axillary temperature measured during the study in all the three groups showed comparable values with insignificant P values.

Study observed that; Most of the patients in Group-A had the mean intra-operative PR ranging from 78.0 to 79.93. Similarly patients in Group-B had the mean intra-operative pulse rate from the range of 79.5 to 80.6, All the time duration mean pulse rate values observed significantly higher in Group-B compare to Group-A, statistically not significant (P<0.05).

Table 2: Comparison of heart rate between the Groups

Table No 3: Comparison of Intra-operative SBP between the Groups

Study observed that; Most of the patients in Group-A had the mean intra-operative SBP ranging from 110.18 to 126.32. Similarly patients in Group-B had the mean intra-operative SBP from the range of 116.46 to 130.80. The time duration mean SBP values at 0 minutes, 1 minutes, 5 minutes, 30 minutes, 60 minutes, 90 minutes and 120 minutes observed significantly higher in Group-B as compare to Group-A, which shows statistically not significant (P>0.05). And the time duration mean SBP values at 10 minutes, 15 minutes observed significantly higher in Group-B as compare to Group-A, which shows statistically significant (P<0.05)

Table  4: Comparison of Intra-operative DBP between the Groups A & B

Study observed that; Most of the patients in Group-A had the mean intra-operative DBP ranging from 73.01 to 75.46. Similarly patients in Group-B had the mean intra- operative Heart rate from the range of 74.32 to 76.78. The duration mean DBP values at 0 minutes, 1 minutes 2 minutes, 5 minutes 10 minutes, 60 minutes, 90 minutes and 120 min. and 15 minutes and 30 minutes observed significantly higher in Group-B as compare to Group-A, which shows statistically significant (P<0.05). Whereas there was statistically no significant difference of mean DBP at 15 minutes and 30 minutes between both Groups. (P>0.05).

Study observed that; Most of the patients in Group-A had the mean intra-operative MAP ranging from 86 to 91 similarly patients in Group-B had the mean intra-operative MAP from the range of 89 to 92. The time duration mean MAP values at 0 minutes, 1 minutes, 5 minutes, 10 minutes and 120 minutes observed significantly higher in Group-B as compare to Group-A, which shows statistically not significant (P>0.05). Where as the time duration mean MAP values at 30 minutes, 60 minutes and 90 minutes observed significantly higher in Group-B as compare to Group-A, which shows statistically significant (P<0.05)

Table 5: Comparison of Intra-operative MAP between the Groups A & B

Table No 6: Comparison of Intra-operative SPO2 between the Groups A and B

Study observed that; Most of the patients in Group-A had the mean intra-operative SPO2 ranging from 98.50 to 99. Similarly patients in Group-B had the mean intra-operative SPO2 in the range of 98.22 to 98.82. The time duration mean SPO2 values at 0, minutes, 1 minutes, 5 minutes, 10 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes and 120 minutes observed higher in Group-A as compare to Group-B, which shows statistically not significant (P>0.05) .

Table 7: Comparison of complications between the Groups A and Group-B

Study observed that, the complication of hypotension cases were seen in Group-B 7 (14.0%) and in Group-A 2 (4.0%) shows statistically no significant difference of hypotension between Group-A and Group-B (P>0.05)

The complication of Bradycardia cases were seen in Group-A 3 (6.0%) and in Group-B 5 (10.0%), shows statistically no significant difference of bradycardia between Groups(P>0.05. The complications of Nausea, Vomiting seen more cases in Group-B as compare to Group-A which shows statistically significant (P<0.05) No cases with decreased SPO2 levels seen in both the groups. No rescue drug was given in both the groups.

Graph 1: Bar diagram presents comparison of complications between the Groups A and Group-B

In our study, most of the patients in Group-A had the mean intra-operative HR ranging from 78.0 to 79.93. Similarly patients in Group-B had the mean intra-operative HR from the range of 79.5 to 80.6. All the time duration mean pulse rate values observed significantly higher in Group-B as compare to Group-A, but statistically not significant (P<0.05). In the study by Usta B et al, majority of the normal saline group had mean heart rate ranging from 88 to 85 bpm and in dexmedetomidine group it was ranging from 90 to 70 bpm between baseline and 110 min intra operatively.4

In Group-A, the mean intra-operative SBP ranged from 110.18 to 126.32, while in Group-B it ranged from 116.46 to 130.80. SBP values were significantly higher in Group-B at 10 and 15 minutes (P<0.05), but not at other times (P>0.05). Group-A's mean intra-operative DBP ranged from 73.01 to 75.46, while Group-B's DBP ranged from 74.32 to 76.78. DBP was significantly higher in Group-B at most times except 15 and 30 minutes (P>0.05). Group-A's mean intra-operative MAP ranged from 86 to 91, while Group-B's MAP ranged from 89 to 92. MAP was significantly higher in Group-B at 30, 60, and 90 minutes (P<0.05). The study observed that most patients in Group-A had a mean intra-operative SPO2 ranging from 98.50 to 99, while in Group-B it ranged from 98.22 to 98.82. At all measured times (0, 1, 5, 10, 15, 30, 60, 90, and 120 minutes), the mean SPO2 values were higher in Group-A compared to Group-B. However, these differences were not statistically significant (P>0.05). Similar to our studies, Kranke P et al evaluated the efficacy of many pharmacological drugs in the treatment of shivering, and concluded there is no significant difference in parameters of heart rate, arterial blood pressure, respiratory rate, spo2, cutaneous temperature and level of sedation5. In the study by Usta B et al, majority of the normal saline group had mean arterial pressure ranging from 90 to 88 mm of Hg and in dexmedetomidine group it was ranging from 90 to 78 mm of Hg between baseline and post operatively respectively. The association between the intervention groups and mean arterial pressure was considered to be not statistically significant both at baseline and post operatively.4

Study observed that, the complication of hypotension cases were seen in Group- B 7 (14.0%) and in Group-A 2 (4.0%) shows statistically no significant difference of hypotension between Group-A and Group-B (P>0.05) The complication of Bradycardia cases were seen in Group-A 3 (6.0%) and in Group-B 5 (10.0%), shows statistically no significant difference of bradycardia between Group-A and Group-B (P>0.05). The complications of Nausea, Vomiting seen more cases in Group-B as compare to Group-A which shows statistically significant (P<0.05). No cases with decreased SPO2 levels seen in both the groups. Hypotension and bradycardia are known hemodynamic effects of dexmedetomidine but only few patients have those side effects which is acceptable as concluded by Lim fern et al6. Hypotension and bradycardia were seen more in group B when compared with group A when compared and it was contrary to concluded by Usta B et al were dexmedetomidine group had more of cases with hypotension and bradycardia.4

The axillary temperatures measured between the groups were comparable and no significant differences was found

Dexmedetomidine had less incidence of nausea, vomiting, hypotension and bradycardia when compared to tramadol. So, it can be used as a better alternative drug for shivering prophylaxis in patients undergoing surgeries under regional anaesthesia.

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